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参数资料
| 型号： | LT3430IFE-1#TR |
| 厂商： | LINEAR TECHNOLOGY CORP |
| 元件分类： | 稳压器 |
| 英文描述： | 6.5 A SWITCHING REGULATOR, 120 kHz SWITCHING FREQ-MAX, PDSO16 |
| 封装： | 4.40 MM, PLASTIC, TSSOP-16 |
| 文件页数： | 4/28页 |
| 文件大小： | 321K |
| 代理商： | LT3430IFE-1#TR |
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LT3430/LT3430-1
12
34301fa
Reduced Inductor Value and Discontinuous Mode
If the smallest inductor value is of most importance to a
converter design, in order to reduce inductor size/cost,
discontinuous mode may yield the smallest inductor solu-
tion. The maximum output load current in discontinuous
mode, however, must be calculated and is dened later
in this section.
Discontinuous mode is entered when the output load
current is less than one-half of the inductor ripple current
(ILP-P). In this mode, inductor current falls to zero before
the next switch turn on (see Figure 8). Buck converters
will be in discontinuous mode for output load current
given by:
IOUT
Discontinuous Mode
<
+
()(
–
)
()(
)( )()
VV V
V
Vf L
OUT
F
IN
OUT
F
IN
2
The inductor value in a buck converter is usually chosen
large enough to keep inductor ripple current (ILP-P) low;
this is done to minimize output ripple voltage and maximize
output load current. In the case of large inductor values,
as seen in the equation above, discontinuous mode will
be associated with “light loads.”
When choosing small inductor values, however, discontinu-
ous mode will occur at much higher output load currents.
The limit to the smallest inductor value that can be chosen
is set by the LT3430/LT3430-1 peak switch current (IP) and
the maximum output load current required, given by:
IOUT(MAX)
Discontinuous Mode
=<
ILP-P
2
=
()
+
I
If L V
VV V
V
P
PIN
OUT
F
IN
OUT
F
2
()(
)
()(
–
)
ILP-P
Example: For VIN = 15V, VOUT = 5V, VF = 0.52V, f = 200kHz
and L = 4.7H.
IOUT(MAX)
Discontinuous
Mode
=
+
3
200 10
4 7 10
15
2 5 0 52 1550 52
23
6
(
)( .
)( )
(.
)(
– – .
)
IOUT(MAX)
= 1.21A
Discontinuous Mode
What has been shown here is that if high inductor ripple
current and discontinuous mode operation can be tolerated,
small inductor values can be used. If a higher output load
current is required, the inductor value must be increased.
If IOUT(MAX) no longer meets the discontinuous mode
criteria, use the IOUT(MAX) equation for continuous mode;
the LT3430/LT3430-1 are designed to operate well in both
modes of operation, allowing a large range of inductor
values to be used.
Short-Circuit Considerations
The LT3430/LT3430-1 are current mode controllers. They
use the VC node voltage as an input to a current compara-
tor which turns off the output switch on a cycle-by-cycle
basis as this peak current is reached. The internal clamp on
the VC node, nominally 2V, then acts as an output switch
peak current limit. This action becomes the switch current
limit specication. The maximum available output power
is then determined by the switch current limit.
A potential controllability problem could occur under
short-circuit conditions. If the power supply output is
short circuited, the feedback amplier responds to the
low output voltage by raising the control voltage, VC, to its
peak current limit value. Ideally, the output switch would
be turned on, and then turned off as its current exceeded
the value indicated by VC. However, there is nite response
time involved in both the current comparator and turnoff
of the output switch. These result in a minimum on time
tON(MIN). When combined with the large ratio of VIN to
(VF + I R), the diode forward voltage plus inductor I R
voltage drop, the potential exists for a loss of control.
Expressed mathematically the requirement to maintain
control is:
ft
VI R
V
ON
F
IN
≤
+
APPLICATIONS INFORMATION
相关PDF资料 |
PDF描述 |
|---|---|
| LT3430EFE-1#TR | 6.5 A SWITCHING REGULATOR, 120 kHz SWITCHING FREQ-MAX, PDSO16 |
| LT3430IFE-1 | 6.5 A SWITCHING REGULATOR, 120 kHz SWITCHING FREQ-MAX, PDSO16 |
| LT3430EFE-1 | 6.5 A SWITCHING REGULATOR, 120 kHz SWITCHING FREQ-MAX, PDSO16 |
| LT3467AIDDB#PBF | 2.5 A SWITCHING REGULATOR, 2700 kHz SWITCHING FREQ-MAX, PDSO8 |
| LT3467AIDDB | 2.5 A SWITCHING REGULATOR, 2700 kHz SWITCHING FREQ-MAX, PDSO8 |
相关代理商/技术参数 |
参数描述 |
|---|---|
| LT3430IFEPBF | 制造商:Linear Technology 功能描述:Sw. Regulator 3A 200kHz 60V TSSOP16EP |
| LT3431 | 制造商:LINER 制造商全称:Linear Technology 功能描述:High Voltage, 3A,500kHz Step-Down Switching Regulator |
| LT3431EFE | 功能描述:IC REG BUCK ADJ 3A 16TSSOP RoHS:否 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 开关稳压器 系列:- 设计资源:Design Support Tool 标准包装:1 系列:- 类型:升压（升压） 输出类型:固定 输出数:1 输出电压:3V 输入电压:0.75 V ~ 2 V PWM 型:- 频率 - 开关:- 电流 - 输出:100mA 同步整流器:是 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:SOT-23-5 细型，TSOT-23-5 包装:剪切带 (CT) 供应商设备封装:TSOT-23-5 其它名称:AS1323-BTTT-30CT |
| LT3431EFE#PBF | 功能描述:IC REG BUCK ADJ 3A 16TSSOP RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 开关稳压器 系列:- 标准包装:250 系列:- 类型:降压（降压） 输出类型:固定 输出数:1 输出电压:1.2V 输入电压:2.05 V ~ 6 V PWM 型:电压模式 频率 - 开关:2MHz 电流 - 输出:500mA 同步整流器:是 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:6-UFDFN 包装:带卷 (TR) 供应商设备封装:6-SON（1.45x1） 产品目录页面:1032 (CN2011-ZH PDF) 其它名称:296-25628-2 |
| LT3431EFE#TR | 功能描述:IC REG BUCK ADJ 3A 16TSSOP RoHS:否 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 开关稳压器 系列:- 设计资源:Design Support Tool 标准包装:1 系列:- 类型:升压（升压） 输出类型:固定 输出数:1 输出电压:3V 输入电压:0.75 V ~ 2 V PWM 型:- 频率 - 开关:- 电流 - 输出:100mA 同步整流器:是 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:SOT-23-5 细型，TSOT-23-5 包装:剪切带 (CT) 供应商设备封装:TSOT-23-5 其它名称:AS1323-BTTT-30CT |
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